This invention relates to the production of hydroxyapatite.
The batch preparation of TCP by the reaction of lime and phosphoric acid is well known. Due to the inherent nature of batch reaction, however, the volume of TCP produced thereby is necessarily less than could be produced by a continuous process. For example, U.S. Pat. No. 3,387,925 discloses a batch reaction of lime and phosphoric acid wherein the particle size of the TCP is controlled in order to obtain a precipitate of fine particles. In accordance with the invention of the aforementioned patent, it was found that a smaller particle size may be produced by controlling the final pH, the reaction temperature and the rate of addition of the reactants. Thus, the temperature of the reaction is kept within a range of from about 20.degree. to 50.degree. C., the lime slurry is continuously agitated to prevent localized acid build-up and the 20% aqueous phosphoric acid which is used is added to the lime slurry as quickly as possible until the lime slurry is neutralized to a pH of between about 6.7 and 8.5.